This invention relates to traffic signals, and in particular, to traffic signals controlled by a micro-controller.
A pedestrian who wants to cross a street is indeed fortunate to encounter a traffic signal. By pressing a button, usually mounted on a post near the traffic signal, the pedestrian can initiate a pedestrian cycle. During the pedestrian cycle, the traffic signal halts all vehicular traffic for enough time to allow the pedestrian to cross the street.
A conventional traffic signal does not know how much time the pedestrian will require to cross the street. As a result, the time allotted for a pedestrian to cross the street is set to the an average crossing time. However, the pedestrian may be unable to cross the street within the allotted time. For example, the pedestrian may be elderly, handicapped, burdened by luggage, pregnant, or coping with small children. A conventional traffic signal can maroon such pedestrians in the middle of the street, facing a wall of cars inching forward in anticipation of a green light.
A traffic signal according to the invention provides two or more pedestrian-selectable cycles. A pedestrian who uses such a traffic signal can thus select a pedestrian cycle that will provide sufficient time to cross the street.
In one aspect, the traffic signal includes a micro-controller in communication with a switching system. The micro-controller executes a process that controls a signal indicator according to a selected signal cycle. First and second actuators communicate with corresponding first and second terminals of the micro-controller. The first actuator causes the micro-controller to execute a first signal cycle. The second actuator causes the micro-controller to execute a second signal cycle.
The second actuator can be directly connected to the micro-controller. Alternatively, the second actuator can be in wireless communication with the micro-controller. For example, the traffic signal can include a wireless receiver in communication with the micro-controller. A transmitter can then be used to signal the receiver to cause a signal to be sent to an appropriate input terminal of the micro-controller. Examples of wireless receivers include frequency receivers, ultrasonic receivers, optical receivers, microwave receivers, and infrared receivers.
The micro-controller is typically configured to execute a selected pedestrian cycle in response to a signal from one of the first and second actuators. The pedestrian cycle is selected on the basis of which of the first and second actuators provides the signal.
The pedestrian cycles selected by each of the first and second actuators can differ in many ways. However, in one embodiment, the pedestrian cycles have different wait intervals, different walk intervals, different sprint intervals, or any combination thereof.
In another aspect, the invention provides a method for controlling a traffic signal by controlling the traffic signal in accord with a first cycle and detecting an interrupt signal on one of a plurality of input terminals. In response to detecting such an interrupt signal, the first cycle is interrupted and a selected second cycle is executed in place of the first cycle. The second cycle is selected on the basis of which of the input terminals carried the interrupt signal.
A traffic signal according to the invention thus enables a pedestrian to select between two or more pedestrian cycles. This feature can readily be incorporated into existing traffic signals, many of which are already operated by a micro-controller having an unused second input terminal. In such a case, the traffic signal can be retrofitted by reprogramming the micro-controller. In other cases, the micro-controller is simply replaced by one having at least two input terminals.
These and other features of the invention will be apparent from the following detailed description and the accompanying drawings, in which: